HTTP status codes

This is a reference list of HTTP status codes from 100 through 599, covering the five classes defined in RFC 9110: informational, success, redirection, client error, and server error. Each code shows its name and a short description, and the search box filters the list as you type, matching against the code number, the name, and the description text.

What’s in the list?

All the codes registered under RFC 9110, plus a handful of widely used extras that never made it into the core spec but show up constantly in real APIs: 418 (the “I’m a teapot” joke from RFC 2324), 429 (rate limited), and 451 (unavailable for legal reasons). Type “404” or “not found” or “gateway” and the matching rows stay visible while the rest hide, so you don’t have to scroll through five classes of codes to find the one you’re after. Every row also has its own link, so #419 at the end of the page address jumps straight to that code.

What do unofficial codes like 419 and 420 mean?

Some codes come from one framework or server rather than from an RFC, and the list marks them with an “Unofficial” badge. HTTP 419, Page Expired, comes from Laravel. The framework sends it when the CSRF token submitted with a form doesn’t match your session, usually because the session ran out while the page sat open. HTTP 420, Enhance Your Calm, is what Twitter’s old Search and Trends API returned to clients that sent too many requests. The standard code for that is 429. Spring Framework also used 420 for Method Failure, which is now deprecated. Two nginx codes round it out: 444 closes the connection without any response, and 499 means the client hung up before the server finished. You’ll find both in server logs, not in a browser. The last one is 599, which some proxies use for a network connect timeout.

Does it need an internet connection?

No. The list is static data rendered directly in the page, nothing is fetched from a server when you load it or when you search. That also makes the search instant.

When would I reach for this?

It’s handy when you’re debugging an API response and can’t remember whether 422 means the same thing as 400, or when you’re deciding whether a redirect should send back 301, 302, or 308 and need a reminder of how they differ. It also covers the rarer codes you won’t have memorized, like 409 (conflict), 416 (range not satisfiable), or the distinction between 502 (bad gateway) and 503 (service unavailable). See MDN’s HTTP status code reference for more detail on each one.

The five classes give you a quick first read on any response even before you check the exact number. A code starting with 2 means the request succeeded, 3 means you need to follow a redirect, 4 means something was wrong with the request itself, and 5 means the server is the one that failed. That’s why servers, browsers, and API clients often branch on the first digit alone. You don’t need to be a developer to find this useful either, plenty of ordinary error pages just print a bare number, and this list turns that number into a plain-language sentence.